-----Original Message-----
From: Peter Hurley [mailto:peter at hurleysoftware.com]
Sent: Friday, October 10, 2014 7:39 PM
To: Lu Jingchang-B35083; gregkh at linuxfoundation.org
Cc: arnd at arndb.de; linux-serial at vger.kernel.org; linux-arm-
kernel at lists.infradead.org; linux-kernel at vger.kernel.org; Joseph Lo
Subject: Re: [PATCH] serial: of-serial: fix up PM ops on
no_console_suspend

Hi Jingchang,

On 10/09/2014 05:10 AM, Jingchang Lu wrote:

quoted

Mandatorily disabling the uart clock will cause register access hung
on "no_console_suspend". This patch add condition check on it and only
disable the clock with console_suspend_enabled true.

Signed-off-by: Joseph Lo <redacted>
Signed-off-by: Jingchang Lu <redacted>
---
 drivers/tty/serial/of_serial.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/of_serial.c

b/drivers/tty/serial/of_serial.c index 8bc2563..a765399 100644

--- a/drivers/tty/serial/of_serial.c
+++ b/drivers/tty/serial/of_serial.c

@@ -246,7 +246,7 @@ static int of_serial_suspend(struct device *dev)
 	struct of_serial_info *info = dev_get_drvdata(dev);

 	serial8250_suspend_port(info->line);
-	if (info->clk)
+	if (info->clk && console_suspend_enabled)
 		clk_disable_unprepare(info->clk);

This needs to check that _this_ port is the console port, like:

if (info->clk && uart_console(port) && and console_suspend_enabled)
	clk_disable_unprepare(info->clk);

which means you need something like:

struct uart_8250_port *uart = serial8250_get_port(info->line);
struct uart_port *port = &uart->port;

Also, there's another problem with your original patch:
not every of_serial device is an 8250, right?
serial8250_suspend_port() on a port that's not registered with 8250 core
is probably going to blow up.

Which means the body of of_platform_suspend() and of_platform_resume()
should probably look like

switch (info->type) {
#ifdef CONFIG_SERIAL_8250
case PORT_8250 ... PORT_MAX_8250:
{
	/* current body of function */
}
#endif
default:
}

Yes, this should be considered, then serial8250_get_port(info->line) for uart_console() also
should be put in this type switch,  Thanks.

Best Regards,
Jingchang

Regards,
Peter Hurley

quoted

 	return 0;

@@ -256,7 +256,7 @@ static int of_serial_resume(struct device *dev)  {
 	struct of_serial_info *info = dev_get_drvdata(dev);

-	if (info->clk)
+	if (info->clk && console_suspend_enabled)
 		clk_prepare_enable(info->clk);

 	serial8250_resume_port(info->line);